Verb

1 divide society into social classes or castes;
"Income distribution often stratifies a society"

2 form layers or strata; "The rock
stratifies"

3 develop different social levels, classes, or
castes; "Society stratifies when the income gap widens"

4 form, arrange, or deposit in layers; "The fish
are stratified in barrels"; "The rock was stratified by the force
of the water"; "A statistician stratifies the list of names
according to the addresses"